National Pollution Discharge Elimination System (NPDES) 
The City of Newcastle is required to have a National Pollution Discharge Elimination System (NPDES) Phase II Municipal Stormwater Permit under the federal Clean Water Act. In Washington State, the NDPES stormwater permits are regulated by the Department of Ecology (DOE). As part of our NPDES permit, we are required to prepare and submit an Annual Report to Ecology each year, which summarizes the City's efforts to comply with permit requirements. 

Stormwater Planning
The Newcastle Public Works Department continually works to update and improve its Stormwater Managment Plan (SWMP). This process involves revising programs to comply with the updated Municipal Stormwater Permit, as well as implementing new programs and tasks that are new to the permit. 

As part of Newcastle's Surface Water Management Program, and as required by City's Municipal Stormwater Permit, the City has developed a Stormwater Management Action Plan (SMAP) that takes a wholistic approach to watershed management. For more information on May Creek Drainage sub-basin and the City's efforts within it, read the Stormwater Management Action Plan for May Creek

In conjunction with the above, the City has implemented the following programs: 

Public Education and Outreach
Newcastle is working in several ways to connect the community to storm and surface water topics. A major goal is to reduce or eliminate behaviors and practices that cause or contribute to adverse stormwater impacts. Learn more in our Stormwater Public Education and Outreach section. 

Public Involvement and Participation
Learn more in our Stormwater Public Involvement and Participation section. 

MS4 Mapping
As part of the SWMP, Newcastle implements an ongoing program to develop and maintain mapping data for features including, outfalls and known discharge points, receiving water, stormwater treatment and flow control facilities, tributary conveyances, and all connections to the public stormwater system. 

To view these features and more, check out our Newcastle GIS Web App.

Illicit Discharge Detection and Elimination (IDDE)
Newcastle has established a program to identify, trace and remove illicit connections and discharges, including spills, into our surface water. Per Newcastle Municipal Code (NMC) 13.05.025, there are certain prohibited and allowed discharges into surface, stormwater and ground water systems. 

To report a spill of oil or hazardous materials or illicit discharge into our stormwater system or natural waterways, refer to the box on the right side of the page. Examples include construction materials, paint, pesticides, fertilizers, soaps, detergents and sewage. 

If you observe a major spill or discharge that may be dangerous to life and health call 9-1-1 immediately and report it as a non-emergency call.

For more information, see WA Department of Ecology website. 

Controlling Runoff from New Development, Redevelopment & Construction Sites
The City works with local business and property owners to ensure that privately owned stormwater systems are functioning properly by inspecting and requiring maintenance or repairs be completed if necessary. These inspections and regular maintenance help the stormwater systems to function as they were designed and prevents water quality degradation, downgradient erosion, and flooding. The City will notify business or property owners by letter prior when is it time for their next inspection.

For more information see our New Development and Redevelopment page. 

Operations and Maintenance
Stormwater maintenance staff inspect our publicly owned or maintained storm drainage systems on a regular basis to verify the structural integrity of our infrastructure. 

During inspections, City staff also verify that there are not any 
illicit discharges or connections to the stormwater system, as well as check the sediment accumulation levels in structures. 

Based on their inspections, City staff make needed repairs, remove sediment and pollutants from our stormwater system, and perform routine maintenance such as mowing detention ponds. Our stormwater staff protect water quality by removing pollutants from storm drains, ditches, ponds and underground facilities. 

Source Control Business Inspection Program
Starting in 2023, Newcastle will be implementing a Source Control Business Inspection Program. In conjunction with already established programs, such as the Private Drainage Inspection and IDEE Programs. These inspections and subsequent outreach are designed to help educate local businesses that have operations or other activities that have the potential to pollute our stormwater system. 

Any questions regarding this upcoming inspection program, contact Surface Water Program Manager, Brian Miller at [email protected]


If you need to report a hazardous spill or urgent matter 24 hours a day, 7 days a week, call 206-296-3311.

To report a non-hazardous spill during regular business hours
(Monday-Friday, 8 a.m. to 5 p.m.)
Call 425-649-4444

On evenings and weekends call 206-296-3311

For drainage concerns or other water quality concerns, submit a request using SeeClickFix at

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